Label and method for in-mold molding using a label thereof

ABSTRACT

A method for applying a label, and a label for in-mold molding which comprises a printed layer formed on a surface of a non-oriented plastic base film over which a membrane layer for bonding to be welded by the heat of molded article at the time of the in-mold molding is overlapped. The label is inserted into a mold for the in-mold molding, the label is held on the proper position in the mold by vacuum suction, or by static electricity, and a moldable article, such as a container, is molded by injecting, filling the plastics into the mold or by expanding a parison which was placed in the mold.

This is a continuation of application Ser. No. 07/489,523 filed Mar. 7,1990, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a label to be attached to containers,and a method for in-mold molding using such a label.

In most cases of shampoo and rinse containers, paper labels are utilizedon these containers for decreasing cost.

It is also known that a label can be formed by a plastic film, which isplaced in a mold before the container is formed and then in-mold moldingis conducted, whereby a container is formed with a bonded label on thesurface thereof.

Conventional labels for said shampoo and rinse contained which aretypically used and stored in a bathroom where there is frequently hightemperature and humidity, have many disadvantages, for example,mildewing the label, pealing the label off by moisture absorption,providing soiled print, and providing unclear label indicia byimpregnated inks, thereby causing such products to have an unsanitaryfeeling and deteriorating the product image.

Although in-mold labeling of plastic film label which is formed duringcontainer molding overcomes difficulties with paper labels, there isstill a problem during the in-mold molding in that when attempting, takeout a single label from a label supply where many labels are stacked,double or triple labels are often taken out stuck to each other becauseof static electricity generated by friction, so that it is difficult totake out the labels one by one.

Further, during in-mold molding, labels may be deformed and consequentlyaccelerate container deformation.

And, even if container is not deformed, the label may partially rise tothe surface of the container, causing container deformation.

Furthermore, since the printer layer of a label bonded to the containeris generally located on the exterior of the label, it is often damagedby friction or by contact with liquid filled in the container.

SUMMARY OF THE INVENTION

The present invention provides a label for in-mold molding which avoidsmildew under high temperature and humidity enviroments and withoutdamaging the printed layer thereof, and provides a process for in-moldmolding which facilitates taking out the label during in-mold moldingand prevents deformation of the label and the container.

According to the present invention, a label for in-mold moldingcomprises a printed layer formed on a surface of non-oriented plasticbase film, over which a membrane layer for bonding to be welded by theheat of molded article at the time of the in-mold molding is overlapped.

As a non-oriented plastic base film, for example, transparent ortranslucent polypropylene, polyethylene, polyester or polyvinyl chloridemay be used individually or as part of a laminate. These materials maybe used in compatibility with the material of the moldable article likecontainer, and so that their physical properties are compatible as thecase may be.

The printed layer can cover the whole surface of the base film or onlypart of it.

And, when polypropylene and other high transparency plastic film is usedfor plastic base film, the printed layer can be seen through from theoutside, and it gives a glossy surface since the printed layer is notexposed on the surface of the base film. When translucent material isused for the plastic base film, the printed layer can be seen from theoutside as a frosted image, i.e., giving a different appearance fromthat when transparent material is used.

For the material of the moldable article, polypropylene, polyethylene,polyvinyl chloride, polyester, polystyrene, AS resin orpolyacrylonitrile are used.

As a membrane layer for bonding to be welded by the heat of the moldedarticle at the time of the in-mold molding, for example, low meltingpoint polypropylene film, polyethylene film, PVC film, PET film, amembrane having as a main component heat weldable adhesive wax, amembrane having as a main component co-polymer of ethylene vinylacetete, or any membrane having as a main component polyvinyl acetalpolymer, polyvinyl alcohol polymer, polyacryl acid esteric polymer,vinyl chloride polymer, polyethylene polymer, polyurethane polymer orpolyester polymer.

And, if different materials are used for the moldable article and saidplastic based film with inferior bonding compatibility to each other, agood labeling effect to the molded article can be achieved by using amembrane layer for bonding which has good bonding properties to both ofthe materials.

A number of emboss areas are provided on said membrane layer of thein-mold molding label, so that labels can be taken out one by one from alabel supply in which labels are stored by stacking for in-mold molding.Sticking between the labels is prevented by the provision of the embossareas, by decreasing the generation of static electricity by decreasingthe label contacting area, and by facilitating release of one label fromanother by the existence of air in each space between the labels.

According to the present invention, the in-mold molding method employsthe aforementioned label, and thus the method has a number of advantagescompared with conventional in-mold molding methods.

More particularly, according to the present invention, when said labelis inserted into a mold for the in-mold molding, the label is held onthe proper position in the mold by vacuum suction, or by staticelectricity, and the moldable article is molded by injecting, fillingthe plastics into a mold or by expanding a parison placed in a mold,whereby a membrane layer for bonding the label contacts a surface of themolded article, and said membrane layer for bonding is bonded to themolded article by welding by the heat which the molded article has.

In this connection, if emboss areas are provided on the surface of themembrane layer for bonding, any air existing in the space between thecontainer surface and the label is discharged to the exterior throughthe emboss areas.

Further, since the plastic base film of the label is formed ofnon-oriented plastic film, it does not shrink, as oriented film is, bythe heat driven by the in-mold molding, and subsequently it does notcause any deformation of the molded article accompanied with suchshrinkage.

And, when labeling is made to the molded article, the printed layer ispositioned in the rear side of the plastic base film and is protected bythe plastic base film, and thus the printed layer is not damaged byfriction, and in cases where the molded article is a container, it isalso not damaged by liquid contained therein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged cross sectional view showing a part of a label ofan embodiment according to the present invention, and,

FIG. 2 are views showing step of a process of molding in accordance withthis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the in-mold molding label 6 according to this inventioncomprises a printed layer 2 formed on the rear surface of a plastic basefilm 1 made of transparent non-oriented polypropylene having a thicknessof 110μ, a membrane layer for bonding 4 laminated on said printed layer2, through an adhesive 3 made of synthetic resin, the membrane layer forbonding 4 adapted to be welded by the heat of the molded article at thetime of the in-mold molding, the membrane layer being made of lowmelting point polypropylene film having a thickness of 30μ. And, on thesurface of said membrane layer for bonding 4, emboss areas 5 areprovided.

In the aforementioned embodiment, the polypropylene film of the plasticbase film 1 may have a thickness of about 75μ˜130μ, and the low meltingpoint polypropylene film of the membrane layer for bonding 4 may have athickness of about 15μ˜45μ.

If, in the above embodiment, the material of said membrane layer forbonding 4 is capable of being bonded to the rear surface of the plasticbase film 1 wherein the printed layer 2 is formed, the membrane layerfor bonding 4 can be attached to the plastic based film 1 without usingadhesive 3.

Now an embodiment of an in-mold molding method according to thisinvention is described.

First, the molding equipment, as shown in FIG. 2 (a), consists of labelsupply unit 10 and container blow molding mold halves 11, 11, one ofwhich has a suction orifice 12 which opens to a cavity, and said orifice12 is connected with vacuum a suction unit 13, whereby a label 6supplied from said label supply unit 10 is held in the mold (FIG. 2 (b))by sucking a label 6 to the position of the suction orifice 12 by meansof vacuum pressure by vacuum suction unit 13.

The label supply unit 10 has a label storing portion 14 and a labelsupply member 15. In said label storing portion 14, a number of labels 6are stored by stacking. The label supply member 15 has a cupule 17 onthe top end of a movable arm 16 enabling a label 6 to be supplied to theposition of the suction orifice 12 in a mold 11 by moving the arm 16 andsucking by said cupule 17 a top positioned label 6 from the storedlabels in the label storing portion 14. Of course, setting the label 6into the mold 11 by taking out from the label storing portion 14 can bedone by manual operation by an operator.

After setting a label 6 into the mold 11, a parison 21 or tubular shapedpreform is placed in the mold 11, and the mold halves are clamped (FIGS.2 (c), (d)), and then a container 22 is blow-molded by expanding withair from a compression air source 23. By expanding the parison 21 orpreform, the membrane layer for bonding 4 of label 6 contacts thesurface of the container 22, so that said membrane layer for bonding 4is bonded on the surface of the container 22 by welding by the heat ofthe container 22 from the blow-molding step (FIG. 2 (e)).

According to the present invention, since a non-oriented plastic basefilm 1 is used for the label 6, even though the label 6 is heated up bythe in-mold molding, it does not deform the container 22 by shrinkingthe label 6, and label 6 itself has no phenomenon such as rising up tothe surface of the container. Thus, the desired shape of the containercan be obtained.

Further, as emboss areas 5 are provided on the surface of the membranelayer for bonding 4, when the labels 6 are stacked for the in-moldoperation, contacting areas of each of the labels 6 are decreased,static electricity generated by friction is also decreased, and labels 6are not stuck together due to the existence of air in each space betweenthe labels 6, whereby a label 6 can be taken out easily one by one, thusincreasing the operation efficiency.

Further, any air between the moldable container 22 and the label 6during the in-mold molding is easily discharged through the emboss areas5, and almost no air remains between the label 6 and the container 22.Thus, the entire surface of the label 6 is hermetically completelybonded to the container 22. This phenomenon is even more remarkablyeffective with larger label sizes.

Such obtained container 22 is protected by the plastic base film 1 whichprotects the printer layer 2 located at a rear side of the label 6 frombeing damaged by friction or liquid within the container 22, and thesurface of the plastic base film 1 is kept glossy because the printedlayer 2 is not exposed on the surface.

What is claimed is:
 1. A label for a molded article formed by in-moldmolding, the label comprising:a non-oriented plastic base film layer; aprinted layer formed on a surface of the non-oriented plastic base film;and a membrane layer for bonding said label to said molded article bybeing welded by heat from said molded article at the time of in-moldmolding, said membrane layer overlapping said printed layer.
 2. A labelas set forth in claim 1, wherein emboss areas are provided on a surfaceof said membrane layer.
 3. A label as set forth in claim 1, wherein saidplastic base film has a thickness of 75μ˜130μ, and said membrane layerhas a thickness of 15μ˜45μ.
 4. A label as set forth in claim 1 whereinsaid membrane layer comprises a material selected from the groupconsisting of heat weldable adhesive wax, co-polymer of ethylene vinylacetate, polyvinyl acetal polymer, polyvinyl alcohol polymer, polyacrylacid esteric polymer, vinyl chloride polymer, polyethylene polymer,polyurethane polymer and polyester polymer.
 5. A label as set forth inclaim 1 wherein said membrane layer is a plastic film.
 6. A label as setforth in claim 5 wherein said membrane layer is adhered by adhesive onsaid surface of plastic base film on which said printed layer is formed.7. A label as set forth in claim 5 wherein said membrane layer comprisesa material selected from the group consisting of low melting pointpolypropylene film, polyethylene film, PVC film, and PET film.